Verified answer

bjr

(2x+1)(x-4)-3 (2x+1)(x+3)

facteur commun (2x+1)

= (2x+1) ((x-4) - 3(x+3))

= (2x+1) ( x - 4 - 3x - 9)

= (2x+1) (-2x - 13)

développement

tu sais que (a+b) (c+d) = ac + ad + bc + bd

donc

= 2x² - 8x + x - 4 - 3 (2x² + 6x + x + 3)

= 2x² - 7x - 4 - 6x² - 21x - 9

= -4x² - 28x - 13

Verified answer

Bonjour,

Développer :

(2x+1)(x-4)-3 (2x+1)(x+3)

= 2x² - 8x + x - 4 - 3 (2x² + 6x + x + 3)

= 2x² - 8x + x - 4 - 6x² - 18x - 3x - 9

= 2x² - 6x² - 8x - 18x - 3x + x - 4 - 9

= - 4x² - 28x - 13

Factoriser :

(2x+1)(x-4)-3 (2x+1)(x+3)

= (2x + 1) [(x - 4) - 3 (x + 3)]

= (2x + 1) (x - 4 - 3x - 9)

= (2x + 1) (x - 3x - 4 - 9)

= (2x + 1) (- 2x - 13)